Hydrometer



T. MIDGLEY,IR.- HYDROMETER, APPLICATION FILED JULY 30, I917.

lA fima Patented Oqt. 24,1922

c me Oct. at, 1922.

THOMAS MIDGLEY,- JR., 'OF DAYTON,

DEBUG-LIGHT OOMPANY, F DAYTON, OHIO, A GORPORATION OF DELAWARE.

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Application filed July 30,' ].91 7; Serial No. 183,486. I.

- To all whom it may concern: Be it known that I, THOMAS M nster,- T1, a citizen of the United States of Amen 10a residing'at ,city' of Dayton in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Hydrometers, of which the following is a,

full, clear, and exact description.

- The present invention relates to improvements in hydrometers and particularly tothat class of hydrometers used in connection with secondary batteriesfor the'purpose of indicating the degree of charge thereof.

One of the objectsof the present invention is to provide a hydrometer which may be I permanently submerged withinthe battery electrolyte, and which will operate efficiently insubmergedposition.

A further object of the present invention is to provide a hydrometer adapted to be permanently submerged within the electrolyte of the battery, and having provisions for compensating for. the variations ture of-the battery electrolyte.

-A- further object of the present invention is to provide a hydrometer including a-carryingorscale member of such materialas to be free from adhesion of gas generated within the battery.

the method of determining the proper loca-. tion of the hydrometer within the battery electrolyte, so that it will be least affected in its. operation by terv electrolyte.

While the above are a few of the objects of the present inventiomother objects and .ad-

vantages will be ap arent from the foregoing description,'re erence beinghad to the 'accompan ing drawing, wherein one preferred em odim'ent of the present invention is clearly illustrated.

'In the drawing:

Fig. l is a view in side elevation of a battery. cellwherein a hydrometer, including the present inve'ntion,is mounted.

-Figs. 2 and 2 are detailed views of the stationary indicating'element which also provides a mounting for the hydrometer.

Fig. 3 is a view'in side elevation of the Q in tempera a v the battery Another feature of the present invention is the stratification of the bat:-

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hydrometer'mernber removedfrom the bat- *tery cell, the stationary shown in Figs. ,2 and 2*, view in dotted lines.

Fig. 4 is a sectional View. taken on the line 44 of Fig. '3.

Fig; 5.is a detailed view of the displace-- ment member or weight-element of the-hydrometer.

Referring to the drawing, and more parindicating element, being shown in this ticularly'to Fig. l, the numeral 20 indicates porting'element or stationary'indicating ele :nlent 25. l y' In the present form of the invention the supporting element 25 is shown as being secured 'to one of the walls of the battery jar,-

but it will be readily seen that this element may be supported by attaching the sameto end wall of t e battery jar.- This supporting element is preferably celluloid, although certain other materials may be used.

As stated above, the scale member .24 is pivotally mounted on the supportingel'ement "25 by means of the point contact 26, which is formed by cutting away a portion of the scale-member, adjacent the center thereof as,

at 27 (see Fig. This construction in reality furnishes a' knife-edge bearing for the scale member 24. on the supporting elementv 25. v

It has been found in practice that beneath the surface of the electrolyte this mounting is practically frictionless and is preferable to other constructions which create greater friction in the operation of the hydrometer. The scale member 24 carries a scale 28, the position of'which with respect to the-stationary indicating element 25, indicates the degree of charge within the battery.

lplate which is adjacent to the- Any approved scale may be used, reading either in specific gravity, Baum, per cent charge, or an arbitrary scale towcorrespond specific gravity than the heaviest specific.

gravitywhich will be encountered in the electrolyte'of the'cell during operation.

"One preferred material for constructingthis scale member is celluloid, and I have discovered a method of preparing the same which overcomes the objections heretofore prohibiting its 'use as a hydrometer' mate rial.

The main objection to the use of celluloid in hydrometrs, has been'that bubbles of gastend toclingto the surface ofthe celluloid, and thereby cause errors in the indicating.

operation of the hydrometer.

My new process of preparing celluloid for "use in hydrometer work, consists in scouring or washingthe celluloid with any suitable mixture which will render the celluloid chemically clean; One form of mixture sodium cyanide. The

may include powdered pumice stone and celluloid is first scoured with this solution and then rinsed in distilled water, and then should be kept free from dust or any foreign matternntil placed in use.

Upon the first operation of the battery in.

. which gassing occurs for a considerable pe riod, the action of the electrolyte tendsto. complete thepreparation. of the celluloid, after which no further gas bubbles will adhere to the celluloid.

A rubber displacement member or weight element 29 is combined with the scale member 24, and is constructed by substantially the same processor method as that disclosedin .my vco-pending Patent,-- No.

1,335,253, dated March 30,1920.

However, it should be understood that' certain additional features are present in the method of pre aring-and usingthis .displacement mem er in the present'invention,

i over the method disclosed in the above-men tioned patent. For instance, in the present process of preparing the displacement mem ber, the degree or: amount of vulcanization of the displacement member is carefully de termined, so that the proper degree of ex pension and contractiomdue to the. variations in temperature of'the battery electrolyte, may be secured.

The method of operation of the present form of myinvention may be. described as follows, reference being had to Fig. l of the drawing: :Ihehydrometer, when in the central position disclosed in Fig. 1, indicates fin Fig. 1.

to sink to the bottom of the cell. .placement member, however, being rigidly connected to or carried by the scale member sideration, is substantially the same as the specific gravity of the electrolyte when the hydrometer is in the balanced position shown However, if the battery cell is further discharged below its half-charged'point, the

specific gravity of the electrolyte will diminish or become li hter, and therefore the dis-- placement mem er 29 will. of course tend This dis- 24 must necessarily carry the scale member with it, and therefore a clockwise movement of the scale member will result. This clockwise movement of the scale member will be about the center of the knife-edge contact on the support 25 and will be practically frictionless, due to the type of support, de-

scribed heretofore.

In' order'to secure a proper and correct reading of the scale member toindicatethe degree or-percentage of charge of the battery cell, the scale member is provided with a projecting finger or counterweight ortion 30, which, as the scale member ten s to move in a clockwise direction, due to the influenceof the displacement member 29, will tend-to oppose th sclockwise movement and tend to return the scale member to its balanced position, shown in Fig. 1.

It willio f course be understood that as the displacementmember tends to carry the scale member further in a clockwise direction, the force of this counter-weightportion 30 will also increase, and I have so proportioned this counterweight portion 30 with relation the scale member from its central position has moved to such a position as to properly indicate the degree of discharge of the better cell.

twill be apparent thatif the battery .11 is charged above the half-char ed point, conditions exactlyopposite to t ose describedabove will come intoplay, rendering the hydrometer operative in the same way, but in an opposite direction to correctly indicate the degreeof charge.

It has been found in practice that a movement of the hydrometer of 45 degrees each way from the central position, causes most satisfactory results, but this movement may be increased to 60 degrees each way without to the displacement member 29 that a. stateand scope of the invention.

form of embodiment of the invention, it is to be understood thatother formsmight be adopted without departing from the spirit What I claim is as-follows: -1 12' A hydrometer-for electrolytic cells and the like, comprising in combination, a mov-- able hydrometer Y and scale memberv "com:- pletely submerged within thev electrolyte' oii' the cell, and meanSQfor supporting the'hyv ;=ment member mounted at one side thereof drometer and scale member, said means con; stituting' an indicating element adapted to cooperate with. the scale. member upon movement thereoftoindicate the condition of charged the cell. o

and a suppo'rt for the hydrometer and scale,

member," the support carrying indicatingmeans adapted to cooperate withjthe" scale memberto indicate the state of charge of.

the like; comprising,in;c0mbination, anfel'ectrolytic cell, with'a, supporting device SB-- cured thereto and located at a'level of the electrolyte least aflectedbystratification, and a hydrometer and scale member completelysubmerged'within the electrolyte of the cell and mounted for movement on'said support. i 4

' 14 A hydrometer member adapted to be pivot ally 40 is directly beneath its support at sub-- v stantially" on supported and comprising a counter-weight portion soar-ranged that the cen-' ter of gravity of the hydrometermember stantially the midp'ositi'on ofthe rangeof movement of the h drometer member, and a displacement mem er secured thereto-Imbstantially on fa horizontal line with the support. 5. A

of the maximum to betested and having its center of gravity directly beneath its sup-' port when immersedin a fiuidfof specific gravityfsubstan'tially midway between the maximum and minimum to betested; and a displacement member secured theretosub- 'a; horizontal line with the sup- .P rt...-'-- 1 6. A hydrometer electrolytic "cells and a the like, comprisingin .jcombination, a scale maximum member of specific gravity greater than the having a specific gravity-intermediate be pivotally' supported: hydrometer. member having- -a'specific gravity in excessspecificgravity of the electrolyte and adapted to be supported' submerged tween the substantial maximum and. minimum of the specific gravity of the electrolyte.

7 A hydrometer for electrolytic cells and is intermediate between the maximum and the minimum specific-gravity of the electrolyte i i 8. A h drometer for electrolytic cells and the like, 'comprislng" a flat fan shaped member carrying-a scale, and with a displacehaving a specific gravity differing from'that of the fan shapedmembe'r.

9. A' hydrometer for electrolytic cells and 1 the like, comprising in'combina-tion, an elec- 2. A hydrometer for electrolytic cellsv and,- the like,fcomprising, in combination, a moy ii able hydrometer and scale" memberf sub-f merged within ,the. electrolyte of the cell} tion projecting from the scale member to counter-balance the displacement member,

"with the center of-gravity otthe combined scale-and displacement members located below the center ofsupport.

-' 10.. The methodof pre-treating the celluloid-'of'a hydrometer member for electrolyitic cells which consists in first chemically eaning-thesurface of the celluloid by washingthe same with a solution containing sodium cyanide and then celluloid fora short time to the gassing electrolyte.

11. A hydrometerfor electrolytic cells and the like, comprising in combination, an electrolytic cell, with a unitary hydrometer and scale member submerged within the electrolyte of the celland movable therein to indi-' cate the condition of charge of the cell, said hydrometer including'a displacement member whose coefiicientof expansion is such as ar ations 1n the tempera- .to compensate for ture of the electrolyte; f

121 A hydrometer for electrolytic' cells' and fthe'like, .trolytic cell-, with-a unitary hydrometer and comprising in combination, an elecs'calememberj'completely submerged twithin the" electrolyte efthe cell and 'movable therein? to indicatethe condition of charge of thecell, said hydrometer including a displacement member of rubber which has been cured in'such amanner that its coeflicient of expansion will-compensate'for variations in temperature of the electrolyte;

loid 'of a hydrometer member for electro- .lytit: cells which consists in first chemically cleaning the surface of the celluloidby washing the same with a solution containing so- 13. The method of pre-treating the cellusubjecting the dium cyanide and pumice stone and then tia-lly the mid-position of the'rang e of movesubjecting the celluloid for a short time to ment of the hydrometer member, and a disthe gassing electrolyte. 3 placement member secured thereto to one 14. A material for hydrometers, consisting 'side'of said support. 5 of celluloid washed in sodium cyanide. In testimony whereof I aflix my signature 15 15. A hydrometer member adapted to in the presence of two subscribing witnesses. be pivotally supported and comprising .a THOMAS MIDGLEY, JR. counter-weight portion so arranged that the Witnesses: j center of gravity of the hydrometer member WALTER W. RIEDEL,

10 is directly beneath its support at substan- J. W. MCDONALD. 

